Two different ways? Well, if I'm understanding correctly, then one of the glows was from Open Fire, which causes cannons to glow yellow. The other glow was simply Skull and Bones' granting me a percentage chance to fire Fury shots.

Knowledge and anticipation of the enemy ships' firing patterns and AI movement comes from years of always sailing the seas in this game. Typically, I always sail to the right with my camera facing the enemy. The reason for going right is because enemy ships will always turn to their left if they either turn to begin firing or get close enough to you, unless there is another ship on their left side.

Soloing these Fleets all started once the EITC Expedition Fleets were sent off to Live. But it wasn't always easy. At first, it was tricky, because I hadn't yet developed the strategy or recognized their attack patterns (as Fleet ships and any ships with the same sort of AI have a slightly different attack pattern from regular ships). At first, I would attempt to switch between cannons and steering, but it wasn't as effective.

War Sloops were always the best choice of ship class to use against these things. Back when I'd first successfully soloed a Fleet without sinking once, Ship Customization hadn't yet been implemented, and I only had a measly 7200 HP to work with, which honestly added to the difficulty and made it more fun. But since I'd learned to only use steering rather than mounting the cannons, it meant I would have to boost a few key skills - five points on both Broadsides, Open Fire and Take Cover, and a few others I can't remember. With Ship Customization, I was able to give my War Sloop Skull and Bones, which in my opinion works best for a War Sloop rather than other hull upgrades because it does not make the ship any slower, it boosts the overall HP by a nice amount, and the added chance to fire Fury makes up for the seven broadside cannons you're limited with. I also gave my War Sloop the Open Fire rigging to allow Open Fire to last just a bit longer.

Another strategy I use is to fire off the broadside, then use Open Fire before it hits. The Open Fire rigging helps with this. The cannonballs fired will still recognize the Open Fire upon impact of the enemy, and right away I also use Leadership to charge up the second broadside quickly enough. Open Fire's duration will last long enough for the second broadside to hit with the added damage just before it wears off.

The only challenge in soloing the Fleets was always simply dealing with the War Frigates. Upon engagement, two of the Fleet ships will always break away in pursuit to attack you, and the rest will follow but at a slower speed. As you sink one, another will begin to speed up to take its place. Once three are down, the Ship of the Line will charge in. As the enemy Ship of the Line (to me) always felt like it moved slightly faster than the War Frigate, it becomes tricky to deal with the remaining one, so usually I would instead start going in the opposite direction. In the video, however, I was lucky enough to get in a position where the HMS Victory was behind me. 'Course, the Ogre had gotten in my way anyway.

Finishing the Ship of the Line was probably the easiest but more time consuming half of the video, as that's about 330000 (as I'd calculated as a test once a good few months ago by estimating - not an exact number however, but more or less good enough). And with viciously durable hull armor, it takes a while to break her down. But once you do, it's easy going. I usually like to carry the Ship of the Line out to Uncharted Waters for a few reasons - mostly due to the open space, and to avoid crossing paths with other players who may negate the solo attempt.

There were only two things that kept me going with soloing Fleets -
1: It was the only truly fun challenge that was left in the game. Foulberto is alright, but he loses his worth since he only drops Throwing Knives and no gold whatsoever. Fleets on the other hand at least offer rewards such as cargo, loot containers and ship materials, and require a bit of strategy. However, I won't disagree that soloing Foulberto isn't a challenge in its own right either - it too requires strategy, and I remember someone in Partners N Crime had actually done it, but I forget who the fellow was. The picture or thread must be somewhere.
Plus, sailing was, again, my favorite aspect of the game.

2: I had never seen it done anywhere else. I have seen one or two videos of Fleet solo attempts, but I felt that they weren't done with care or strategy. One in particular, the player rushed in and simply bombarded them with something until they sank - that is not how it is done. Anyone could solo a Fleet if all you had to do was sink a few hundred times in the process. Plus, you risk not being able to finish it in time, as (back then) either the Fleet will despawn upon the next hour, or it will just reach the end and all that sinking and gold wasted for repairs will be for nought.
Though I do not wish to put myself on a high horse, I feel as though I am the only person to actually show a successful Fleet solo with a War Sloop without sinking once - and in just over 20 minutes (when I had my regular War Sloop, it took nearly the whole 50 minutes that a Fleet exists). I won't doubt that no one else has done it, but I can't say I've ever seen any documented accounts of a Fleet solo. Hence, it makes me proud to be the one to be able to do something like this.